CALLR - CALLR is an extremely helpful app for those who have to deal with call control protocols for their business. You can create a customized call control system that will perform a wide range of functions.

Twilio - Brings voice and messaging to your web and mobile applications.

GoToMeeting - GoToMeeting is a web conferencing service offering a range of services which are available on Mac, PC, iOS and Android devices.

Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates

MySalesDialerPro - MySalesDialerPro offers a complete solution that helps sales reps perform end-to-end sales process.

Clockwork SMS - Clockwork is an Easy Text Message API. An SMS API for Developers. Build powerful apps and include SMS. Signup is free, Try it now.